Apparatuses for reading out X-ray information stored in a storage phosphor layer are used in particular in the field of computer radiography (CR) for medical purposes. An image of an object, for example a patient or a body part of the patient, is produced here by means of X-ray radiation, and this is stored in a storage phosphor layer as a latent image. This type of X-ray image therefore contains X-ray information about the object. In order to read out the X-ray information stored in the storage phosphor layer, the storage phosphor layer is stimulated by means of an irradiation device. As a result of this stimulation, the storage phosphor layer emits light which has an intensity corresponding to the X-ray information stored in the storage phosphor layer. The light emitted from the storage phosphor layer is collected by a detection device and is converted into electric signals, which contain an image of the X-ray information. The electric signals are further processed, and the X-ray information stored in the storage phosphor layer is then made visible. The X-ray information can be shown directly on a monitor, for example, or by means of a printer used specially for X-ray images, on a photographic X-ray film.
The storage phosphor layer is generally applied to a support layer, and these together form a storage phosphor plate. In order to correctly read out the storage phosphor layer, the storage phosphor plate is generally required to have a high degree of levelness. In this way, signal fluctuations in the detected signal, and so image errors, are largely prevented. In order to achieve this levelness, with some variations of read-out apparatuses, the storage phosphor plate is pressed onto a level support or sucked onto the support. It is also possible to attach magnets, both to the storage phosphor plate and to the support, and these guarantee level positioning of the storage phosphor plate. The disadvantage of these variations, however, is that they require a relatively large installation space, are associated with additional weight, and require costly mechanics.